Solid polymer membrane for fuel cell with polyamine imbibed therein for reducing methanol permeability

ABSTRACT

The present invention provides for a solid polymer electrolyte membrane having a fluorinated ionomer having imbibed therein a non-fluorinated, non-ionomeric polymer, wherein the fluorinated ionomer comprises at least 6 mole % of monomer units having a fluorinated pendant group with a terminal ionic group, and wherein the non-ionomeric polymer is selected from the group consisting of a polyamine, a polyvinyl amine, and derivatives thereof. The invention also provides a catalyst coated membrane and a fuel cell having this solid polymer electrolyte membrane.

FIELD OF THE INVENTION

[0001] The present invention relates for a direct methanol fuel cellthat employs a solid polymer electrolyte membrane, and more particularlyrelates to certain solid polymer electrolyte membrane compositions.

BACKGROUND OF THE INVENTION

[0002] Direct methanol fuel cells (DMFCs), fuel cells in which the anodeis fed directly with liquid or vaporous methanol, have been underdevelopment for a considerable period of time, and are well-known in theart. See for example Baldauf et al, J. Power Sources, vol. 84, (1999),Pages 161-166. One essential component in a direct methanol, or any,fuel cell is the separator membrane.

[0003] It has long been known in the art to form ionically conductingpolymer electrolyte membranes and gels from organic polymers containingionic pendant groups. Well-known so-called ionomer membranes inwidespread commercial use are Nafion® perfluoroionomer membranesavailable from E. I. du Pont de Nemours and Company, Wilmington Del.Nafion® is formed by copolymerizing tetrafluoroethylene (TFE) withperfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride), as disclosed inU.S. Pat. No. 3,282,875. Other well-known perfluoroionomer membranes arecopolymers of TFE with perfluoro (3-oxa-4-pentene sulfonyl fluoride), asdisclosed in U.S. Pat. No. 4,358,545. The copolymers so formed areconverted to the ionomeric form by hydrolysis, typically by exposure toan appropriate aqueous base, as disclosed in U.S. Pat. No. 3,282,875.Lithium, sodium and potassium are all well known in the art as suitablecations for the above cited ionomers.

[0004] Other fluorinated ionomer membranes are known in the art such asthose described in WO 9952954, WO 0024709, WO 0077057, and U.S. Pat. No.6,025,092.

[0005] DMFCs employing ionomeric polymer electrolyte membranes asseparators are known to exhibit high methanol cross-over—the transportof as much as 40% of the methanol from the anode to the cathode bydiffusion through the membrane. This methanol cross-over essentiallyrepresents a fuel leak, greatly decreasing the efficiency of the fuelcell. In addition, the presence of methanol at the cathode interfereswith the cathode reaction, with the methanol itself undergoingoxidation, and, in sufficient volume, floods the cathode and shuts downthe fuel cell altogether. Methanol cross-over occurs primarily as aresult of the high solubility of methanol in the ionomeric membranes ofthe art.

[0006] It is of considerable interest in the art to identify ways toreduce methanol cross-over in ionomeric membranes while entailing assmall as possible cost in conductivity.

[0007] Kyota et al, JP Sho 53(1978)-60388, describes a process forproducing modified Nafion® membranes with reduced permeability tohydroxide ion by swelling with a solvent or liquid, diffusing apolymerizable vinyl monomer into the swollen matrix with an initiator,and polymerizing in situ. Also disclosed by reference is a process fordiffusing the monomers without solvent-swelling, but thesolvent-swelling process is said to be superior. Methanol permeabilityis not discussed.

[0008] Seita et al, U.S. Pat. No. 4,200,538, disclose a cation exchangemembrane prepared by swelling a fluorinated ionomer with an organicsolvent, removing the solvent, immersing in a vinyl monomer, addinginitiators and other additives, and polymerizing the monomer in situ.Improvements in hydroxyl ion permeability are noted. Suitable monomersinclude styrene and styrene derivatives; acrylic, methacrylic, andmaleic acids and salts and esters thereof; vinyl acetate, vinylisocyanate, acrylonitrile, acrolein, vinyl chloride, vinylidenechloride, vinylidene fluoride, vinyl fluoride; and numerous others.Methanol permeability is not discussed.

[0009] Fleischer et al, U.S. Pat. No. 5,643,689, disclose compositemembranes which include combination of ionomeric polymers and numerousnon-ionic polymers including polythyleneimine and polyvinylpyrrolidone.Metal oxides are present in the composite. The composites are preparedby dissolving the respective polymers in a common solvent and thenremoving the solvent, and are said to be useful in hydrogen fuel cells.

[0010] Li et al, WO 98/42037, discloses polymer electrolyte blends inbatteries. Disclosed are blends of polybenzimidazoles with Nafion® andother polymers in concentration ratios of ca. 1:1. Preferred are blendsof polybenzimidazoles and polyacrylamides. Polyvinylpyrrolidone andpolyethyleneimine are also disclosed.

SUMMARY OF THE INVENTION

[0011] In a first aspect, the invention provides a solid polymerelectrolyte membrane comprising a fluorinated ionomer having imbibedtherein a non-fluorinated, non-ionomeric polymer, wherein thefluorinated ionomer comprises at least 6 mole % of monomer units havinga fluorinated pendant group with a terminal ionic group, and wherein thenon-ionomeric polymer is selected from the group consisting of apolyamine, a polyvinylamine, and derivatives thereof.

[0012] In the first aspect, the polyamine is selected from the groupconsisting of polyvinylpyrrolidone and polyethyleneimine.

[0013] In a second aspect, the invention provides a catalyst coatedmembrane comprising a solid polymer electrolyte membrane having a firstsurface and a second surface, an anode present on the first surface ofthe solid polymer electrolyte membrane, and a cathode present on thesecond surface of the solid polymer electrolyte membrane, wherein thesolid polymer electrolyte membrane comprises a fluorinated ionomerhaving imbibed therein a non-fluorinated, non-ionomeric polymer, whereinthe fluorinated ionomer comprises at least 6 mole % of monomer unitshaving a fluorinated pendant group with a terminal ionic group, andwherein the non-ionomeric polymer is selected from the group consistingof a polyamine, a polyvinyl amine, and derivatives thereof.

[0014] In the second aspect, the polyamine is selected from the groupconsisting of polyvinylpyrrolidone and polyethyleneimine.

[0015] In a third aspect, the invention provides a fuel cell comprisinga solid polymer electrolyte membrane, wherein the solid polymerelectrolyte membrane comprises a fluorinated ionomer having imbibedtherein a non-fluorinated, non-ionomeric polymer, wherein thefluorinated ionomer comprises at least 6 mole % of monomer units havinga fluorinated pendant group with a terminal ionic group, and wherein thenon-ionomeric polymer is selected from the group consisting of apolyamine, a polyvinyl amine, and derivatives thereof.

[0016] In the third aspect, the polyamine is selected from the groupconsisting of polyvinylpyrrolidone and polyethyleneimine.

[0017] In the third aspect, the fuel cell further comprises an anode anda cathode present on the first and second surfaces of the polymerelectrolyte membrane.

[0018] In the third aspect, the fuel cell further comprises a means fordelivering fuel to the anode, a means for delivering oxygen to thecathode, a means for connecting the anode and cathode to an externalelectrical load, methanol in the liquid or gaseous state in contact withthe anode, and oxygen in contact with the cathode. The fuel is in theliquid or vapor phase. Some suitable fuels include alcohols such asmethanol and ethanol; ethers such as diethyl ether, etc.

BRIEF DESCRIPTION OF DRAWINGS

[0019]FIG. 1 is a schematic illustration of a single cell assembly.

[0020]FIG. 2 is a schematic illustration of a typical DMFC test station.

[0021]FIG. 3 is a graph showing the performance of a DMFC using Sample120-3, Example 13 at an operating temperature of 38° C.

[0022]FIG. 4 is a graph showing the performance of a DMFC using Sample130-6, Example 13 at an operating temperature of 38° C.

DETAILED DESCRIPTION

[0023] Following the practice of the art, in the present invention, theterm “ionomer” is used to refer to a polymeric material having a pendantgroup with a terminal ionic group. The terminal ionic group may be anacid or a salt thereof as might be encountered in an intermediate stageof fabrication or production of a fuel cell. Proper operation of thefuel cell of the invention requires that the ionomer be in acid form.The term “polymeric precursor” to an ionomer suitable for use in thepresent invention refers to the non-ionic form of a polymer which whensubject to hydrolysis according to well-known methods in the art isconverted into the ionomer suitable for use in the present invention, ora salt thereof.

[0024] Also for the purposes of the present invention the term“polyamine” refers to polymers having an amine functionality in themonomer unit, either incorporated into the backbone, as inpolyalkyleneimines, or in a pendant group as in polyvinyl amines. Theterm “polyamine” will be employed to encompass polymers variously knownas polyamines, polyamides, polyimines, polyimides, and polyvinyl amines,amides, imines, and imides. By “derivatives thereof” we mean

[0025] wherein R or R′ is alkyl of 1 to 16 carbon atoms, more typically1 to 5 carbon atoms, and aryl of 6-20 carbon atoms, more typically 6 to8 carbon atoms.

[0026] The term “membrane precursor” refers to a membrane formed fromthe ionomer suitable for the practice of the invention, prior to theformation of a blend with another polymer which is not an ionomer inorder to produce the composite ionomeric polymer electrolyte membrane ofthe invention. It is not necessary for the practice of the inventionthat a precursor membrane first be formed followed by incorporation of apolymer which is not an ionomer to form the composite membrane of theinvention. For example, it is possible in some cases to melt blend theionomeric precursor and the polymer which is not an ionomer followed bymelt casting a film and hydrolysis. In other cases, it is possible todissolve the ionomer or its precursor and the other polymer which is notan ionomer in a common solvent, and then solution cast a film. However,it is found in the practice of the invention that it is convenient tofirst fabricate a membrane precursor from the ionomer or its precursorfollowed by imbibing the non-fluorinated, non-ionomeric polymer therein.

[0027] It is found that the polymer electrolyte membrane comprising afluorinated ionomer having imbibed therein another polymer which is notan ionomer provides a reduction in methanol and water permeability atrelatively modest cost, if any, in conductivity to provide an improvedDMFC.

[0028] A membrane comprising a fluorinated ionomer having imbibedtherein a polyamine has utility in electrochemical cells with particularutility in DMFCs. One of ordinary skill in the art will understand thatthe film or sheet structure will have utility in packaging, innon-electrochemical membrane applications, as an adhesive or otherfunctional layer in a multilayer film or sheet structure, and otherclassic applications for polymer films and sheets which are outsideelectrochemistry. For the purposes of the present invention, the term“membrane,” a term of art in common use in the fuel cell art issynonymous with the terms “film” or “sheet” which are terms of art inmore general usage but refer to the same articles.

[0029] Membrane:

[0030] Ionomers suitable for use in the present invention comprise atleast 6 mol % of monomer units having a fluorinated pendant group with aterminal ionic group, preferably a sulfonic acid or sulfonate salt. A“polymeric precursor” to an ionomer suitable for use in the presentinvention preferably comprises a sulfonyl fluoride end-group, which whensubject to hydrolysis under alkaline conditions, according to well-knownmethods in the art, is converted into a sulfonic acid or sulfonate salt.

[0031] Any direct methanol fuel cell known in the art, of the typeprovided with an ionomeric polymer electrolyte membrane may be employedin the present invention. It is by the substitution of a membranecomprising a fluorinated ionomer having imbibed therein a polymer whichis not a fluorinated ionomer, according to the teachings of the presentinvention, for the ionomeric membrane of the art that the benefits ofthe present invention are realized.

[0032] It has been found that solid polymer electrolyte membranes of theinvention that are particularly well suited for use in fuel cells, andin particular direct methanol fuel cells, have a surprisingly largedecrease in methanol permeability at a relatively small, if any,sacrifice in conductivity.

[0033] A membrane in accordance with the invention comprises anionomeric polymer or ionomer, having imbibed therein a non-ionomericpolymer. The ionomer suitable for the practice of the invention hascation exchange groups that can transport protons across the membrane.The cation exchange groups are acids preferably selected from the groupconsisting of sulfonic, carboxylic, phosphonic, imide, methide,sulfonimide and sulfonamide groups. Various known cation exchangeionomers can be used including ionomeric derivatives oftrifluoroethylene, tetrafluoroethylene, styrene-divinylbenzene, alpha,beta, beta-trifluorostyrene, etc., in which cation exchange groups havebeen introduced alpha, beta, beta-trifluorstyrene polymers useful forthe practice of the invention are disclosed in U.S. Pat. No 5,422,411.

[0034] Ionomeric Polymers:

[0035] In one embodiment of the invention, the ionomer comprises apolymer backbone and recurring side chains attached to the backbone withthe side chains carrying the cation exchange groups. For example,ionomers are formed by copolymerization of a first fluorinated vinylmonomer and a second fluorinated vinyl monomer having a side cationexchange group or a fluorinated cation exchange group precursor (e.g.,SO₂F) which can be subsequently hydrolyzed to sulfonic acid groups.Possible first monomers include but are not limited totetrafluoroethylene, hexafluoropropylene, vinyl fluoride, vinylidinefluoride, trifluorethylene, chlorotrifluoroethylene, perfluoro(alkylvinyl ether), and mixtures thereof. Possible second monomers include butare not limited to a variety of fluorinated vinyl ethers withfluorinated cation exchange groups or precursor groups.

[0036] In a further embodiment, the ionomer in accordance with theinvention has a backbone which is substantially fluorinated and the ionexchange groups are sulfonic acid groups or alkali metal or ammoniumsalts thereof which are readily converted to sulfonic acid groups by ionexchange. “Substantially fluorinated” means that at least 60% of thetotal number of halogen and hydrogen atoms are fluorine atoms. In afurther embodiment, the ionomer backbone and the side chains are highlyfluorinated, particularly perfluorinated. The term “highly fluorinated”means that at least 90% of the total number of halogen and hydrogenatoms are fluorine atoms.

[0037] Some ionomers suitable for use in the present invention arevariously described in U.S. Pat. No. 4,358,545, U.S. Pat. No. 4,940,525,WO 9945048, U.S. Pat. No. 6025092. Suitable ionomers as disclosedtherein comprise a highly fluorinated carbon backbone having at least 6mol % of a perfluoroalkenyl monomer unit having a pendant groupcomprising the radical represented by the formula

—(OCF₂CFR)_(a)OCF2(CFR′)_(b)SO₂X⁻(H⁺)[YZ_(c)]_(d)  (I)

[0038] wherein

[0039] R and R′ are independently selected from F, Cl or aperfluoroalkyl group having 1 to 10 carbon atoms, optionally substitutedby one or more ether oxygens;

[0040] a=0, 1 or 2;

[0041] b=0 to 6;

[0042] X is O, C or N with the proviso that d=0 when X is O and d=1otherwise, and c=1 when X is C and c=0 when X is N;

[0043] when c=1, Y and Z are electron-withdrawing groups selected fromthe group consisting of CN, SO₂R_(f),SO₂R³, P(O)(OR³)₂, CO₂R³, P(O)R³ ₂,C(O)R_(f), C(O)R³, and cycloalkenyl groups formed therewith whereinR_(f) is a perfluoroalkyl group of 1-10 carbons optionally containingone or more ether oxygens; R³ is an alkyl group of 1-6 carbonsoptionally substituted with one or more ether oxygens, or an aryl groupoptionally further substituted;

[0044] or, when c=0, Y may be an electron-withdrawing group representedby the formula —SO₂R_(f)′ where R_(f)′ is the radical represented by theformula

—(R_(f)″SO₂N—(H⁺)SO₂)_(m)R_(f)′″

[0045] where m=0 or 1, and R_(f)″ is —C_(n)F_(2n)— and R_(f)′″ is—C_(n)F_(2n+1) where n=1-10

[0046] Most preferably, the ionomer comprises a perfluorocarbon backboneand said pendant group is represented by the formula

—OCF₂CF(CF₃)—OCF₂CF₂SO₃H

[0047] Ionomers of this type are disclosed in U.S. Pat. No. 3,282,875.

[0048] The equivalent weight (a term of the art defined herein to meanthe weight of the ionomer in acid form required to neutralize oneequivalent of NaOH) of the ionomer can be varied as desired for theparticular application. Where the ionomer comprises a perfluorocarbonbackbone and the side chain is represented by the formula

—[OCF₂CF(CF₃)]_(n)—OCF₂CF₂SO₃H

[0049] where n=0 or 1. The equivalent weight when n=1 is preferably800-1500, most preferably 900-1200. The equivalent weight when n=0 ispreferably 600-1300.

[0050] In the manufacture of the preferred membranes wherein the ionomerhas a highly fluorinated backbone and sulfonate ion exchange groups, amembrane precursor is conveniently initially formed from the polymer inits sulfonyl fluoride form since it is thermoplastic and conventionaltechniques for making films from thermoplastic polymers can be used.Alternatively, the ionomer precursor may be in another thermoplasticform such as by having —SO₂X groups where X is alkoxy such as CH₃O— orC₄H₉O—, or an amine. Solution film casting techniques using suitablesolvents for the particular polymer can also be used if desired.

[0051] The ionomer precursor polymer in sulfonyl fluoride form can beconverted to the sulfonate form (i.e, ionic form) by hydrolysis usingmethods known in the art. For example, the membrane may be hydrolyzed toconvert it to the sodium sulfonate form by immersing it in 25% by weightNaOH for about 16 hours at a temperature of about 90° C. followed byrinsing the film twice in deionized 90° C. water using about 30 to about60 minutes per rinse. Another possible method employs an aqueoussolution of 6-20% of an alkali metal hydroxide and 5-40% polar organicsolvent such as dimethyl sulfoxide with a contact time of at least 5minutes at 50-100° C. followed by rinsing for 10 minutes. Afterhydrolyzing, the membrane can be converted if desired to another ionicform by contacting the membrane in a bath containing a 1% salt solutioncontaining the desired cation or, to the acid form, by contacting withan acid and rinsing. For fuel cell use, the membrane is usually in thesulfonic acid form.

[0052] If desired, the membrane precursor may be a laminated membrane oftwo or more ionomeric precursors such as two highly fluorinated ionomershaving different ion exchange groups and/or different ion exchangecapacities. Such membranes can be made by laminating films orco-extruding a multi-layer film. In addition, the ionomeric component ofthe composite membrane suitable for use in the present invention may beitself a blend of two or more ionomers such as two or more highlyfluorinated ionomer preferred for the practice of the invention whichhave different ion exchange groups and/or different ion exchangecapacities. It is also possible to form a multilayer structureincorporating one or more layers of the composite membrane of theinvention.

[0053] The thickness of the membrane can be varied as desired for aparticular electrochemical cell application. Typically, the thickness ofthe membrane is generally less than about 250 μm, preferably in therange of about 25 μm to about 150 μm.

[0054] The membrane may optionally include a porous support for thepurposes of improving mechanical properties, for decreasing cost and/orother reasons. The porous support of the membrane may be made from awide range of components. The porous support of the present inventionmay be made from a hydrocarbon such as a polyolefin, e.g., polyethylene,polypropylene, polybutylene, copolymers of those materials, and thelike. Perhalogenated polymers suchas polychlorotrifluoroethylene mayalso be used. For resistance to thermal and chemical degradation, thesupport preferably is made of a highly fluorinated polymer, mostpreferably perfluorinated polymer.

[0055] For example, the polymer for the porous support can be amicroporous film of polytetrafluoroethylene (PTFE) or acopolymer oftetrafluoroethylene with other perfluoroalkyl olefins or withperfluorovinyl ethers. Microporous PTFE films and sheeting are knownwhich are suitablefor use as a support layer. For example, U.S. Pat. No.3,664,915 discloses uniaxially stretched film having at least 40% voids.U.S. Pat. Nos. 3,953,566, 3,962,153 and 4,187,390 disclose porous PTFEfilms having at least 70% voids.

[0056] Alternatively, the porous support may be a fabric made fromfibers of the support polymers discussed above woven using variousweaves such as the plain weave, basket weave, leno weave, or others. Amembrane suitable for the practice of the invention can be made bycoating the porous support fabric with an ionomeric polymer havingimbibed therein a non-ionomeric polymer to form a composite membrane ofthe invention in situ on the porous support. To be effective the coatingmust be on both the outside surfaces as well as distributed through theinternal pores of the support. This may be accomplished by impregnatingthe porous support with a solution or dispersion of the blend ofionomeric and non-ionomeric polymers suitable for the practice of theinvention using a solvent which is not harmful to the polymer of thesupport under the impregnation conditions and which can form a thin,even coating of the composite blend on the support. The support with thesolution/dispersion is dried to form the membrane. If desired, thinfilms of the ion exchange polymer can be laminated to one or both sidesof the impregnated porous support to prevent bulk flow through themembrane that can occur if large pores remain in the membrane afterimpregnation.

[0057] It is preferred for the cation exchange ionomer to be present asa continuous phase within the membrane.

[0058] Other forms of the solid polymer electrolyte membrane include thePTFE yarn embedded type and the PTFE fibril dispersed type, wherein thePTFE fibril is dispersed in the ion exchange resin as disclosed in 2000Fuel Cell Seminar (10/30 to 11/2, 2000, Portland, Oreg.) Abstracts,p-23.

[0059] Non-Fluorinated, Non-ionomeric Polymers and Formation ofMembranes:

[0060] The membrane composition further comprises a non-fluorinated,non-ionomeric polymer. The selection of non-ionomeric polymers suitablefor use in the polymer electrolyte membrane is quite wide. It isdesirable that the second polymer be chemically and thermally stableunder conditions of use in a fuel cell. It is preferred that the secondpolymer may comprise a relatively high frequency of dipolar monomerunits but is not itself ionic. A “high frequency” of dipolar monomerunits means that the mole percentage concentration of monomer unitshaving dipolar functionality should be at least 75%, and is preferablygreater than 90%. A “high frequency” of dipolar monomer units also meansthat the monomer units of which the dipolar moiety is a part should beas short as possible to increase the frequency of occurrence of thedipolar moiety. Thus a vinyl monomer would be preferred over, forexample a butenyl monomer.

[0061] The non-ionomeric polymer may be dissolved to form a solution ina solvent that is also a swelling agent for the ionomer that is alsoprepared separately. In a preferred embodiment, a polyamine, mostpreferably polyvinylpyrrolidone or polyethyleneimine, is dissolved in asolvent in which the ionomer is also swollen. A preferred solvent is amixture of tetrahydrofuran (THF) and water. In the preferred embodiment,the polyamine is dissolved in the THF/H₂O mixture, then a preformedmembrane of the ionomer is immersed in the solution for a period of upto several hours in order to achieve the desired level of non-ionomericpolymer in the ionomer.

[0062] When prepared according to the methods taught herein, thenon-ionomeric polymer is usually well dispersed in the ionomer orpolymeric precursor thereto. It has been observed in the practice of theinvention that polyamine concentrations of as little as about 0.2% byweight, more typically as little as about 1% by weight, based on theweight of the solid polymer electrolyte membrane, can providesignificant reductions in methanol permeability while maintainingconductivity at a high level. Polyamines may be used in concentrationsthat do not deleteriously affect the membrane. For example, up to about50% of the polyamine concentration may be used, more typically about 1to about 10%.

[0063] One of skill in the art will recognize that the polymerelectrolyte membrane compositions of the invention wherein the membranecomprises polyamine will have utility in hydrogen fuel cells, includingreformed hydrogen fuel cells, as well as in direct methanol fuel cells.Hydrogen fuel cells are well known in the art. Use of the ionomericpolymer membrane comprising polyamine is contemplated in any or allhydrogen fuel cell designs. The specific design of and materialssuitable for hydrogen fuel cells are largely encompassed by thefollowing discussion that is primarily aimed at direct methanol fuelcells. That is to say, a hydrogen fuel cell must have an anode, acathode, a separator, an electrolyte, a hydrogen feed, an oxygen feed, ameans for connecting to the outside, and such other components as areindicated in FIG. 1 with the substitution of hydrogen for methanol. Oneof ordinary skill will recognize that for the purpose of the presentinvention, a hydrogen fuel cell includes a reformed hydrogen fuel cell.

[0064] Membrane Electrode Assemblies (MEAs) and Electrochemical Cells

[0065] One embodiment of a fuel cell suitable for the practice of thepresent invention is shown in FIG. 1. While the cell depicted representsa single-cell assembly such as that employed in determining some of theresults herein, one of skill in the art will recognize that all of theessential elements of a direct methanol fuel cell are shown therein inschematic form.

[0066] A ionomeric polymer electrolyte membrane of the invention, 11, isused to form a membrane electrode assembly, 30, (MEA) by combining itwith a catalyst layer, 12, comprising a catalyst, e.g. platinum,unsupported or supported on carbon particles, a binder such as Nafion®,and a gas diffusion backing, 13. The ionomeric polymer electrolytemembrane of the invention, 11, with a catalyst layer, 12, forms acatalyst coated membrane, 10, (CCM). The gas diffusion backing maycomprise carbon paper which may be treated with a fluoropolymer and/orcoated with a gas diffusion layer comprising carbon particles and apolymeric binder to form an membrane electrode assembly (MEA). The fuelcell is further provided with an inlet, 14, for fuel, such as liquid orgaseous alcohols, e.g. methanol and ethanol; or ethers such as diethylether, etc., an anode outlet, 15, a cathode gas inlet, 16, a cathode gasoutlet, 17, aluminum end blocks, 18, tied together with tie rods (notshown), a gasket for sealing, 19, an electrically insulating layer, 20,and graphite current collector blocks with flow fields for gasdistribution, 21, and gold plated current collectors, 22.

[0067] The fuel cell utilizes a fuel source that may be in the liquid orgaseous phase, and may comprise an alcohol or ether. Typically amethanol/water solution is supplied to the anode compartment and air oroxygen supplied to the cathode compartment. The ionomeric polymerelectrolyte membrane serves as an electrolyte for proton exchange andseparates the anode compartment from the cathode compartment. A porousanode current collector, and a porous cathode current collector areprovided to conduct current from the cell. A catalyst layer thatfunctions as the cathode is in contact with and between thecathode-facing surface of the membrane and the cathode currentcollector. A catalyst layer that functions as the anode is disposedbetween and is in contact with the anode-facing surface of the membraneand anode current collector. The cathode current collector iselectrically connected to a positive terminal and the anode currentcollector is electrically connected to a negative terminal.

[0068] The catalyst layers may be made from well-known electricallyconductive, catalytically active particles or materials and may be madeby methods well known in the art. The catalyst layer may be formed as afilm of a polymer that serves as a binder for the catalyst particles.The binder polymer can be a hydrophobic polymer, a hydrophilic polymeror a mixture of such polymers. Preferably, the binder polymer is anionomer and most preferably is the same ionomer as in the membrane.

[0069] For example, in a catalyst layer using a perfluorinated sulfonicacid polymer membrane and a platinum catalyst, the binder polymer canalso be perfluorinated sulfonic acid polymer and the catalyst can be aplatinum catalyst supported on carbon particles. In the catalyst layers,the particles are typically dispersed uniformly in the polymer to assurethat a uniform and controlled depth of the catalyst is maintained,preferably at a high volume density. It is typical that the particles bein contact with adjacent particles to form a low resistance conductivepath through catalyst layer. The connectivity of the catalyst particlesprovides the pathway for electronic conduction and the network formed bythe binder ionomer provides the pathway for proton conduction.

[0070] The catalyst layers formed on the membrane should be porous sothat they are readily permeable to the gases/liquids that are consumedand produced in cell. The average pore diameter is preferably in therange of about 0.01 to about 50 μm, most preferably about 0.1 to about30 μm. The porosity is generally in a range of about 10 to about 99%,preferably about 10 to about 60%.

[0071] The catalyst layers are preferably formed using an “ink”, i.e., asolution of the binder polymer and the catalyst particles, which is usedto apply a coating to the membrane. The binder polymer may be in theionomeric (proton) form or in the sulfonyl fluoride (precursor) form.When the binder polymer is in the proton form the preferred solvent is amixture of water and alcohol. When the binder polymer is in theprecursor form the preferred solvent is a perfluorinated solvent (FC-40made by 3M).

[0072] The viscosity of the ink (when the binder is in the proton form)is preferably controlled in a range of 1 to 102 poises especially about102 poises before printing. The viscosity may be controlled by:

[0073] (i) particle size selection,

[0074] (ii) the composition of the catalytically active particles andbinder,

[0075] (iii) adjusting the water content (if present), or

[0076] (iv) preferably by incorporating a viscosity regulating agentsuch as carboxymethyl cellulose, methyl cellulose, hydroxyethylcellulose, and cellulose and polyethyleneglycol, polyvinyl alcohol,polyvinyl pyrrolidone, sodium polyacrylate and polymethyl vinyl ether.

[0077] The area of the membrane to be coated with the ink may be theentire area or only a select portion of the surface of the membrane. Thecatalyst ink may be deposited upon the surface of the membrane by anysuitable technique including spreading it with a knife or blade,brushing, pouring, metering bars, spraying and the like. The catalystlayer may also be applied by decal transfer, screen printing, padprinting or by application from a printing plate, such as a flexographicprinting plate.

[0078] If desired, the coatings are built up to the thickness desired byrepetitive application. The desired loading of catalyst upon themembrane can be predetermined, and the specific amount of catalystmaterial can be deposited upon the surface of the membrane so that noexcess catalyst is applied. The catalyst particles are preferablydeposited upon the surface of a membrane in a range from about 0.2mg/cm² to about 20 mg/cm².

[0079] Typically a screen printing process is used for applying thecatalyst layers to the membrane with a screen having a mesh number ofabout 10 to about 2400, more typically a mesh number of about 50 toabout 1000, and a thickness in the range of about 1 to about 500micrometers. The mesh and the thickness of the screen, and viscosity ofthe ink are selected to give electrode thickness ranging from about 1micron to about 50 microns, more particularly about 5 microns to about15 microns. The screen printing process can be repeated as needed toapply the desired thickness. Two to four passes, usually three passes,have been observed to produce the optimum performance. After eachapplication of the ink, the solvent is preferably removed by warming theelectrode layer to about 50° C. to about 140° C., preferably about about75° C. A screen mask is used for forming an electrode layer having adesired size and configuration on the surface of the ion exchangemembrane. The configuration is preferably a printed pattern matching theconfiguration of the electrode. The substances for the screen and thescreen mask can be any materials having satisfactory strength such asstainless steel, poly(ethylene terephthalate) and nylon for the screenand epoxy resins for the screen mask.

[0080] After forming the catalyst coating, it is preferable to fix theink on the surface of the membrane so that a strongly bonded structureof the electrode layer and the cation exchange membrane can be obtained.The ink may be fixed upon the surface of the membrane by any one or acombination of pressure, heat, adhesive, binder, solvent, electrostatic,and the like. Typically the ink is fixed upon the surface of themembrane by using pressure, heat or a combination of pressure and heat.The electrode layer is preferably pressed onto the surface of themembrane at about 100° C. to about 300° C., most typically about 150° C.to about 280° C., under a pressure of about 510 to about 51,000 kPa(about 5 to about 500 ATM), most typically about 1,015 to about 10,500kPa (about 10 to about 100 ATM).

[0081] An alternative to applying the catalyst layer directly onto themembrane is the so-called “decal” process. In this process, the catalystink is coated, painted, sprayed or screen printed onto a substrate andthe solvent is removed. The resulting “decal” is then subsequentlytransferred from the substrate to the membrane surface and bonded,typically by the application of heat and pressure.

[0082] When the binder polymer in the ink is in the precursor (sulfonylfluoride) form, the catalyst coating after it is affixed to themembrane, either by direct coating or by decal transfer, is subjected toa chemical treatment (hydrolysis) where the binder is converted to theproton (or ionomeric) form.

[0083] The invention is illustrated in the following examples.

EXAMPLES Methanol Permeability

[0084] In order to determine methanol permeability, the membrane sampleswere loaded into a Millipore high-pressure filter assembly modified bythe addition of liquid distribution plates to serve as a permeation testcell having a permeation area of 9.6 cm². The cell was then installedinside an insulated box kept at 80° C.

[0085] A methanol solution, typically about 1M to about 3M, wascirculated on the top side of the membrane at a flow rate of 5.7 cc/min(measured with a rotameter). The bottom of the membrane was swept withnitrogen at 3,000 SCCM measured with mass flow controllers. Both themethanol solution and the nitrogen were heated to the cell temperatureby circulating through stainless steel coils before entering thepermeation cells. Samples of the nitrogen sweeping the permeation cellswere directed to a set of Valco valves and then injected into a HP 6890Gas Chromatograph with a Thermal Conductivity Detector (TCD) and HP-PLOTQ GC Column to determine methanol concentration. The molar flux ofmethanol through the membrane was calculated.

[0086] Conductivity of the subject membrane was determined by impedancespectroscopy by which is measured the ohmic (real) and capacitive(imaginary) components of the membrane impedance. Impedance wasdetermined using the Solartron model SI 1260 Impedance/Gain-phaseAnalyzer, manufactured by Schlumberger Technologies Ltd., InstrumentDivision, Farnborough, Hampshire, England, utilizing a conductivity cellhaving a cell constant of 202.09, as described in J. Phys. Chem., 1991,95, 6040 and available from Fuel Cell Technologies, Albuquerque, N.Mex.

[0087] Prior to the conductivity measurement, a membrane was boiled indeionized water for one hour prior to testing. The conductivity cell wassubmersed in water at 25±1° C. during the experiment.

[0088] The impedance spectrum was determined from 10 Hz to 10⁵ Hz at 0VDC, and 100 mv (rms) AC. The real impedance that corresponded to thehighest (least negative) imaginary impedance was determined.

[0089] Conductivity was calculated from the equation:

conductivity=cell constant/[(real impedance)*(film thickness)]

Example 1 Preparation of Nafion® 117/Polyyinvlpyrrolidone (PVP)Membranes

[0090] To a solution of 10 g PVP (mol. wt. 29,000) in 25 ml H₂O wasadded 25 ml tetrahydrofuran (THF). This caused phase separation. Theupper layer (13 ml) contained THF, water and 0.13 g PVP. The lower layerwas added to a 6 inch×6 inch×0.007 inch (15.25 cm×15.25 cm×0.0178 cm)(8.54 g) Nafion® film in a 1 gallon size polyethylene zip-lock bag.After standing 3 days at room temperature, the film, when wiped dry,weighed 17 9, and 11.25 g when air dried. The film was extractedexhaustively with water with a final 3 hrs in 90° C. water. Theextracted film weighed 12.49 g. The methanol permeability was below thethreshold of detectability. The conductivity was 0.0183 S/cm.

Examples 2-4 and Comparative Example A

[0091] PVP (mol. wt. 29,000) in the amounts shown in Table 2 wasdissolved in 50 ml H₂O, then 44 g of THF were added. There were no phaseseparations. Film specimens of Nafion® 117 approximately 6″×6″×0.007″(15.25 cm×15.25 cm×0.0178 cm) in size were soaked in the solutions forthe times indicated, air dried, and water extracted as in Example 1. Acontrol specimen was soaked in the THF/H₂O solution without PVP, thenwater extracted as in Example 1. Results are shown in Table 2. TABLE 2Example A (Control) Example 2 Example 3 Example 4 Weight PVP in 0 0.631.25 2.5 solution Weight of 8.36 8.11 7.84 8.10 Nafion ® 117 Hours of 35 5 2 Soaking Weight of 11.85 11.88 11.65 11.84 Extracted Film Methanol1.29 0.347 0.135 .0943 Permeability (mol/cm²/min ×10⁵ Conductivity0.0953 0.0796 0.07 0.0576 (S/cm) % change in — −73 −90 −93 permeability% Change in — −16 −27 −40 conductivity

Examples 5-7

[0092] Following the procedures of Examples 2-4, polyethyleneimine (PEI)in the amounts shown in Table 3 was dissolved in 50 ml H₂O after which44 9 of THF were added to give a clear solution. The Nafion(® 117 filmsapproximately 6″×6″×0.007″ (15.25 cm×15.25 cm×0.0178 cm) in size weresoaked in the solutions for the indicated times, air dried, and waterextracted as summarized in Table 3. TABLE 3 Example A (Control) Example5 Example 6 Example 7 Weight PEI in 0 0.68 0.34 0.24 solution Weight of8.36 7.97 7.9 8.07 Nafion ® 117 Hours of Soaking 3 2 2 2 Weight of 11.8510.33 10.36 9.80 Extracted Film Methanol 1.29 0.121 0.0956 0.0011Permeability (mol/cm²/min ×10⁵ Conductivity 0.0953 0.0724 0.0787 0.0791(S/cm) % change in — −91 −93 −99.9 permeability % Change in — −24 −17−17 conductivity

Example 8

[0093] Nafion® 117 film was dried at 185° C. and weighed. It had aweight of 8.06 g. It was then soaked in 29% aqueous solution of PVP(Alfa Aesar) for 3 days. The film was removed, wiped and dried at 30°C., followed by drying at 185° C., and then weighed again to show aweight of 8.17 g. The weight increase of 0.11 g by weight correspondedto a concentration of 1.3% of PVP in the membrane. Conductivity was0.0956 S/cm, and methanol permeability was 1.06×10⁻⁵ mol/cm²/min.

Example 9

[0094] A 6 inch×6 inch×0.007 inch (15.25 cm×15.25 cm×0.0178 cm) specimenof Nafion®117 film was dried at 185° C., and weighed. It had a weight of7.81 g. The film was then soaked in 10% PEI (Aldrich, MW 24,000) watersolution for five hours. After removal, the film was wiped, and dried at150° C. The dried film was soaked in water for 1 hour, dried again, andweighed to show a weight of 7.94 g. The weight difference indicated aconcentration of PEI in the membrane so formed of 1.7%.

Example 10

[0095] The procedures of Example 9 were followed with the exception thatthe film was held clamped while one side of the film was painted withthe PEI solution. The percentage of PEI in the final product was 0.64%.Conductivity was 0.093 S/cm, while methanol permeability was 1.22×10⁻⁵mol/cm²/min. By contrast, a Nafion®117 control specimen which wastreated in a similar manner but without the PEI exhibited methanolpermeability of 2.15×10⁻⁵ mol/cm²/min.

Example 11

[0096] The procedure of Example 10 was repeated except that both sidesof the film were painted. Conductivity was 0.094 S/cm, and methanolpermeability was 0.882 mol/cm²/min.

Example 12

[0097] Permanence of Polyvinylpyrrolidone (PVP) Absorbed into Nafion®

[0098] The purpose of these experiments was to prove that PVP wasirreversibly absorbed by the Nafion®.

[0099] A. Absorption of PVP into Nafion®

[0100] The film was prepared as described in Example 4, cut into piecesand treated as follows: Film Sample # Treatment 83-4 Untreated 83-5Heated at 175° C. for 20 min 83-6 Heated at 30° C. for 2 hrs in 20%aqueous NaOH; and water washed. 83-7 Sample 83-6 is heated at 75° C. for1 hr in 20% HNO₃ (aqueous); and water washed

[0101] All samples had strong carbonyl absorption at 1640 cm⁻¹ Neatpolyvinylpyrrolidone had a strong carbonyl band at 1655 cm⁻¹ This bandin the treated film had been shifted by the Nafion® by 15 cm⁻¹indicating an association between the two polymers.

[0102] To see if any of the PVP had been extracted out of the Nafion®,the 1640 cm⁻¹ band of the absorbed PVP was compared with the 975 cm⁻¹band of Nafion®. The data shown in Table 4 suggested that very little,if any, PVP was extracted. TABLE 4 IR absorbancies of PVP/Nafion ® filmsAbsorbancy of 1640 cm⁻¹ Sample # Absorbancy of 975 cm⁻¹ 83-4 (untreated)1.05 83-5 0.76 83-6 1.35 83-7 0.95

[0103] The PVP/Nafion® ratio changed very little when treated with hotstrong base and acid.

Example 13

[0104] These experiments show the effect molecular weight of PVP playsin Nafion® conductivity and water and methanol transport.

[0105] Nafion®117 film, 12 inch×6 inch×0.007 inch (30.5 cm×15.25cm×0.0178 cm) specimens, were soaked in solutions of PVP dissolved inapproximately 190 g of 50/44 water/THF (by weight) contained in sealedpolyethylene bags. The bags were kneaded and turned over periodically toinsure uniform reaction between the Nafion® and PVP. The films swelledunequally in the film cast direction, and shrunk in the perpendiculardirection. After four hours, the films were measured, weighed wet,dried, measured and weighed again. The films were soaked in deionizedwater for 3 days, weighed, and measured again. The films were cut intotwo essentially equal parts. One part was tested directly.

[0106] The other part was treated sequentially with base and acid asdescribed below:

[0107] The films from above were treated with 20% NaOH at 80-90° C. for2 hours followed by 3 days of soaking in water. The films were thentreated with 20% HNO₃ (by volume of 70% HNO₃ and water) at 80° C., for 2hrs. After a water wash the samples were submitted for testing.

[0108] The following table shows the molecular weight effect on theNafion® films of this example that were treated with the PVP and heatedwith nitric acid and sodium hydroxide solutions. The data shows that allmolecular weights are effective in lowering methanol and water transportthrough Nafion® and the highest molecular weight PVP has the leasteffect on conductivity. Effect of PVP Molecular Weight and a HNO₃/NaOHPost-Treatment of PVP Nafion ® Film HN0₃NaOH Treatment PVP TransportRate Conduc. Trans. Rate Conduc. Code Mol. Wt. mmols CH₃OH* H₂0** mS/cmCode CH₃OH* H₂0** Ms/cm 120-4 10,000 14.1 0.832 4.36 44.2 130-4 0.5273.89 44.7 120-5 29,000 14.1 0.767 3.95 45.0 130-5 0.345 2.16 29.7 120-61.3 × 10⁻⁶ 14.1 1.47 3.07 70.3 130-6 0.745 4.36 104.1 Nafion ® N/A N/A1.87 8.71 100 Control

[0109] The next table shows how the amount of PVP effects theperformance of the Nafion® treated film. From the data, we see that theconductivity decreases with the concentration of the PVP used, and atthe same time transport of methanol and water are generally lowered asthe amount of PVP was increased. It was remarkable that the acid/basetreatment increased conductivity and lowered transport rates of methanoland water. Effect of PVP Concentration On Performance of PVP/Nafion ®Films PVP Transport Rate Conduc. Transport Rate Conduct. Mol. Wt. CH₃OHH₂0 mS/cm Code CH₃OH H₂0 mS/cm 120-3 1.34 × 10⁶ 10.5 1.22 5.08 95.7130-3 0.804 4.34 111.5 120-6 1.34 × 10⁶ 14.1 1.47 3.07 70.3 130-6 0.7454.36 104.1 120-9 1.34 × 10⁶ 2.7 1.33 5.44 95.1 130-9 1.280 7.23 121.2

Example 14

[0110] Copolymer of vinyl pyrrolidone and 2-dimethylaminoethylmethacrylate, quaternized copolymer with Nafion® —SO₃H⁺ form.

[0111] To the above polymer, as a 20% water solution (from Aldrich,average molecular weight less than one million), was added a 6″×6″×7 milNafion® 117 (—SO₃H⁺ form) film, and the resulting film was dried at 180°C. After storing at room temperature for four days, the film was wipeddry, and dried at 50° C. The weight of the film had increased from 8.8 gto 9.3 g.

[0112] The film was then soaked in water for 2 hours and dried again at80° C., to give a weight of 9.32 g. The film had the followingproperties: Permeability for CH₃OH 3.83 × 10⁻⁶ mol/cm²/min for H₂0 2.15× 10⁻⁴ mol/cm²/min Conductivity 0.0154 S/cm.

[0113] The methanol and water permeation rates were lowered three fold.

Example 15

[0114] Polyacrylamide was Imbided into Nafion® Film.

[0115] A Nafion® —SO₃H⁺ 12 inch×6 inch×0.007 inch (30.5 cm×15.25cm×0.0178 cm) film was dried at 180° C., and soaked in 20%polyacrylamide in water (Aldrich) at room temperature for four days. Thefilm was wiped dry with a moist towel, and dried at 150° C. Althoughthere was not a measurable weight gain in the dried film, its propertieswere altered. Rate of permeation H₂0 × 10⁻⁴ mol/cm²/min 5.16 CH₃OH ×10⁻⁶ mol/cm²/min 9.83 Conductivity mS/cm 25

Example 16

[0116] In this example, only one side of the Nafion® film was treatedwith PVP.

[0117] The 12 inch×6 inch×0.007 inch (30.5 cm×15.25 cm×0.0178 cm) insize Nafion® —SO₃H⁺ film was clamped to a 0.125 inch (0.318 cm) plaqueof polytetrafluoroelthylene with book binder clips. Then the exposedside was treated with PVP solution used in Example 12. The film expandedby buckling, but the clips held the film in place and the solution didnot touch the film's underside. The assembly was placed in apolyethylene bag so that the PVP solution would not dry. After 2 hours,the surface was sprayed lightly with a water mist and place back in thesealed bag with a wet paper towel to keep the humidity high for 3 days.The wet towel did not touch the film. The film was rinsed with water,soaked in water for 2 hours, and dried at 180° C.

[0118] Properties, as compared with those of Example 8 are shown below:Nafion ® treated Nafion ® treated Permeation of: on one side on bothsides H₂0 (×10⁻⁴ mol./cm²/min) 5.64 5.82 CH₃OH (×10⁻⁵ mol/cm²/min) 1.191.00 Conductivity (S/cm) 0.0932 0.0956

Example 17

[0119] A copolymer of N-vinyl pyrrolidone and vinylacetate was imbidedinto a 12 inch×6 inch×0.007 inch (30.5 cm×15.25 cm×0.0178 cm) in sizeNafion® —SO₃H⁺ film.

[0120] A solution of the copolymer of 60% viny pyrrolidone and 40%vinylacetate (Aldrich) in methanol was used to imbibe the copolymer intothe Nafion® —SO₃H⁺ film. After 2 hours, the film was removed, dried withpaper towels, followed by methanol wet towels until the surface wascleaned of polymer, and dried at 80° C. Results are shown below:Permeation H₂0 (× 10⁻⁴ mol/cm²/min) 5.230 CH₃OH (×10⁻⁵ mol/cm²/min)0.983 Conductivity, mS/cm 81

Example 18: (Control)

[0121] In this example, a non-polymeric pyrrolidone(N-methylpyrrolidone) was tested. It did nothing to lower water onmethanol transport.

[0122] A 12 inch×6 inch×0.007 inch (30.5 cm×15.25 cm×0.0178 cm) in sizeNafion® —SO₃H⁺ film was dried at 180° C., was stored in 30%N-methylpyrrolidone (NMP) for two hours. The film was soaked in waterfor 3 days and finally dried at 185° C. Results are shown in the tablebelow: Wt. of dried Nafion ® film 7.55 g. Wt. of Nafion ® film soaked in30% NMP, 7.79 (3% NMP) and dried Wt. of Nafion ® film soaked in water,and 7.72 (2% NMP) dried

[0123] The properties of the final film were: Permeation Rate H₂0 (×10⁻⁴ mol/cm²/min) 7.08 × 10⁻⁴ CH₃OH (×10⁻⁵ mol/cm²/min) 1.55 × 10⁻⁵Conductivity, S/cm 0.077

[0124] Membranes prepared as described in Example 13 were tested fortheir performance in a fuel cell using the following procedures:

[0125] Catalyst Coated Membrane (CCM) Preparation Procedure:

[0126] The cathode catalyst dispersion was prepared in a Eiger® beadmill, manufactured by Eiger Machinery Inc., Grayslake, Ill. 60030,containing 80 ml 1.0-1.25 micron zirconia grinding media. 105 gramsPlatinum black catalyst powder (obtained from Colonial Metals, Elkton,Md.) and 336 grams of 3.5 wt % Nafion® solution (the polymer resin usedin such a solution was typically of 930EW polymer and was in thesulfonyl fluoride form) were mixed and charged into the mill anddispersed for 2 hours. Material was withdrawn from the mill and particlesize was measured. The ink was tested to ensure that the particle sizewas under 1-2 micron and the % solids in the range of 26%. The catalystdecal was prepared by drawing down the catalyst ink to a dimension of 5cm×5 cm (to give a total area of 25 cm²) on a 10 cm×10 cm piece of 3 milthick Kapton® polyimide film manufactured by E.I. duPont de Nemours &Co., Wilmington, Del. A wet coating thickness of 5 mil (125 microns)typically resulted in a catalyst loading of 4 to 5 mg Pt/cm² in thefinal CCM. Anode decals were prepared using a procedure similar to thatdescribed above, except that in the catalyst dispersion, the Platinumblack catalyst was replaced by a 1:1 atomic ratio Platinum/Rutheniumblack catalyst powder (obtained from Johnson Mathey, NJ). The CCM wasprepared by a decal transfer method. A piece of wet untreated Nafion®N117 membrane (4″×4″) (10.16 cm×10.16 cm) in the H⁺ form was used forCCM preparation. The membrane was sandwiched between an anode catalystcoated decal and a cathode catalyst coated decal. Care was taken toensure that the coatings on the two decals were registered with eachother and were positioned facing the membrane. The entire assembly wasintroduced between two pre-heated (to 145C) 8″×8″ plates of a hydraulicpress and the plates of the press were brought together without wastingmuch time until a pressure of 5000 lbs was reached. The sandwichassembly was kept under pressure for ˜2 mins and then the press wascooled for ˜2-3 mins (viz., till it reached a temperature of <60° C.)under the same pressure. Then the pressure was released under ambientconditions, and the assembly was removed from the press and the Kapton®films were slowly peeled off from the top of the membrane showing thatthe catalyst coating had been transferred to the membrane. The CCM wasimmersed in a tray of water (to ensure that the membrane was completelywet) and carefully transferred to a zipper bag for storage and futureuse.

[0127] A similar method was used to fabricate the CCMs using the treatedmembranes of the invention with the following exception: the treatedmembranes tested required a slightly higher temperature, e.g. 160° C.,and a higher pressure, e.g. 7000 psi (4.9×10⁶ kg m⁻²) for a completedecal transfer of the catalyst ink to the membrane.

[0128] Chemical Treatment of CCMs

[0129] The CCMs were chemically treated in order to convert the ionomerin the catalyst layer from the —SO₂F form to the proton —SO₃H form. Thisrequires a hydrolysis treatment followed by an acid exchange procedure.The hydrolysis of the CCMs was carried out in a 20 wt % NaOH solution at80° C. for 30 min. The CCM's were placed between Teflon® mesh,manufactured by DuPont, and placed in the solution. The solution wasstirred to assure uniform hydrolyses. After 30 minutes in the bath, theCCM's were removed and rinsed completely with fresh deionized (DI) waterto remove all the NaOH.

[0130] Acid exchange of the CCMs that were hydrolyzed in the previousstep was done in 15 wt % Nitric Acid Solution at a bath temperature of65° C. for 45 minutes. The solution was stirred to assure uniform acidexchange. This procedure was repeated in a second bath containing 15 wt% Nitric acid solution at 65° C. for another 45 minutes.

[0131] The CCMs were then rinsed in flowing DI water for 15 minutes atroom temperature to ensure removal of all the residual acid and finallyin a water bath at 65° C. for 30 minutes. They were then packaged wetand labeled. The CCM (10) comprised an untreated Nafion® 117 or treatedNafion® perfluorinated ion exchange membrane (11); and electrodes (12),prepared from a platinum/ruthenium black catalyst and Nafion® binder onthe anode side, and a platinum black catalyst and Nafion® binder on thecathode side.

Example 19

[0132] The treated and untreated, 7 mil (177.8 microns) Nafion®membranes as shown in Table 5 were evaluated for fuel cell performancein a cell employing a membrane electrode assembly, 30, (MEA) of the typedepicted in FIG. 1. A catalyst coated membrane, 10, (CCM) prepared asdescribed above was loosely attached in a single cell hardware(purchased from Fuel Cell Technologies Inc., NM) with ELAT™ carboncloths, 13, (GDB) purchased from E-Tek, Natick, Mass. In one embodiment,the single side microporous layer coated on the carbon cloth faced thePt—Ru black electrode. In a second embodiment, the ELAT™ carbon clothsare double side coated with microporous layers, wherein one side iscoated thicker than the other, the thicker coated side faced the Ptblack electrode. The active area of the single cell hardware was 25 cm².Care was taken to ensure that the GDB covered the catalyst coated areaon the CCM.

[0133] A glass fiber reinforced silicone rubber gasket (19) (Furan—Type1007, obtained from Stockwell Rubber Company), cut to shape to cover theexposed area of the membrane of the CCM, was placed on either side ofthe CCM/GDB assembly, taking care to avoid overlapping of the GDB andthe gasket material. The entire sandwich assembly was assembled betweenthe anode and cathode flow field graphite plates (21) of a 25 cm²standard single cell assembly (obtained from Fuel Cell TechnologiesInc., Los Alamos, N.Mex.). The single cell assembly shown in FIG. 1 wasalso equipped with anode inlet (14), anode outlet (15), cathode gasinlet (16), cathode gas outlet (17), aluminum end blocks (18), tiedtogether with tie rods (not shown), electrically insulating layer (20),and gold plated current collectors (22). The bolts on the outer plates(not shown) of the single cell assembly were tightened with a torquewrench to a torque of 1.5 ft.lb (0.21 kgf m).

[0134] The single cell assembly (40) was then connected to the fuel celltest station, a schematic illustration of which is shown in the FIG. 2.The components in a test station include a supply of air for use ascathode gas (41); a load box to regulate the power output from the fuelcell (42); a MeOH solution tank to hold the feed anolyte solution (43);a heater to pre-heat the MeOH solution before it enters the fuel cell(44); a liquid pump to feed the anolyte solution to the fuel cell at thedesired flow rate (45); a condenser to cool the anolyte exit from thecell to room temperature (46), a collection bottle to collect the spentanolyte solution (47), and a vent (48) through which exhaust gases andwater are removed.

[0135] With the cell at room temperature, 1M MeOH solution and air wereintroduced into the anode and cathode compartments respectively throughinlets (14) and (16) of the cell at the rates of 5 cc/min and 500 cc/minrespectively to the anode and cathode compartments. The temperature ofthe single cell was slowly raised till it reached 38° C. Typically, acurrent-voltage polarization curve was recorded. This comprised ofrecording the current output from the cell as the voltage was steppeddown in 50 mV steps starting from the open circuit voltage(OCV) down to0.15 V and back up to OCV. The voltage was held constant in each stepfor 20 seconds to allow for the current output from the cell tostabilize.

[0136] An aqueous solution of 1 M methanol was passed over the anodeside and ambient pressure air at room temperature was passed over thecathode side. The cell was heated to 38° C. The current flowing acrossthe cell which was a measure of the fuel cell performance was measuredand recorded by scanning the potential from 0 volt to 0.8 V. The cellpower density (W/cm²) is another performance measure, which wascalculated from the equation, Power Density=Cell current density×Cellvoltage. TABLE 5 Conductivity Sample # Membrane Treatment Details(mS/cm) 1 Nafion ® N117 None 100 (control) 2 Sample 120-3, Nafion ® N11796 Example 13 membrane exposed to 1.17 g PVP in water/THF mixtures for˜2 hrs 3 Sample 130-6, Nafion ® N117 95 Example 13 membrane exposed to1.57 g PVP in water/THF mixtures for ˜2 hrs. and further treated withNaOH and HNO₃

[0137] Results show that the power density for the treated Sample 120-3,Example 13 and Sample 130-6, Example 13 at 0.3V is ˜15% higher than theuntreated commercial Nafion® N117 membrane. The data is shown in FIGS. 3and 4.

Example 20 Methanol Cross-Over Determination

[0138] The same membrane electrode assemblies with Samples 120-3 and130-6, Example 13, used in the previous examples, were used for themethanol crossover measurements. An electrochemical method, as describedby Xiaoming Ren et al in “Proceeding of Proton Conducting Membrane FuelCells I” eds. Shimshon Gottesfeld, Gerald Halpert and Albert Landgrebe,pp 284-298, was followed to determine the methanol crossover rate.Instead of air as mentioned in fuel cell measurements, an inert nitrogengas was fed (500 cc/min) through the cathode side. The anode was fedwith 1M methanol feed, and the cell was heated to 38° C. Once the celltemperature was stabilized to 38° C., the cell was driven from 0.2V to0.8V with 0.05V increments using a power supply (Model #Zup6-66, LambdaElectronics, CA (USA) in conjunction with the fuel cell assemblydescribed previously. The current measured at each voltage steps wasrecorded and limiting current determined from the current vs. voltagecurve, typically at ˜0.8 V was attributed to methanol crossover rate forthe membrane used. The methanol crossover data thus determined is shownin Table 6. TABLE 6 Methanol Crossover (mA/cm²) Temp. MeOH Sample 120-3,Sample 130-6, (° C.) Concn. (M) Control Example 13 Example 13 38 1 55 3644

[0139] It was observed that the methanol crossover rate for the samples120-3 and 130-6, Example 13, was lower than the neat commercialNafion®N117 membrane and reduced by 34 and 20% respectively vs. 2Mmethanol Nafion N117 using a 1M Methanol feed.

Example 21

[0140] Example 20 was repeated with the following exception: Methanolhaving a 2M concentration was used instead of the 1M methanol. Thecrossover rate obtained is shown in Table 7. TABLE 7 Methanol Crossover(mA/cm²) Temp. MeOH Sample 120-3, Sample 130-6, (° C.) Concn. (M)Control Example 13 Example 13 38 2 101 61 77

[0141] The methanol crossover rate was reduced by 39% and 23%,respectively, for Samples 120-3 and 130-6, Example 13 compared to thecommercial Nafion® N117 membrane.

What is claimed is:
 1. A solid polymer electrolyte membrane comprising afluorinated ionomer having imbibed therein a non-fluorinated,non-ionomeric polymer, wherein the fluorinated ionomer comprises ahighly fluorinated carbon backbone having at least 6 mole % of monomerunits having a fluorinated pendant group with a terminal ionic group,and wherein the non-ionomeric polymer is is selected from the groupconsisting of a polyvinyl amine, and derivatives thereof.
 2. The solidpolymer electrolyte membrane of claim 1 wherein the polyvinylamine ispolyvinylpyrrolidone.
 3. The solid polymer electrolyte membrane of claim1 wherein the fluorinated pendant group is the radical represented bythe formula —(OCF₂CFR)_(a)OCF₂(CFR′)_(b)SO₂X⁻(H⁺)[YZ_(c)]_(d)  (I)wherein R and R′ are independently selected from F, Cl or aperfluoroalkyl group having 1 to 10 carbon atoms, optionally substitutedby one or more ether oxygens; a=0, 1 or 2; b=0 to 6; X is O, C or N withthe proviso that d=0 when X is O and d−1 otherwise, and c=1 when X is Cand c=0 when X is N; when c=1, Y and Z are electron-withdrawing groupsselected from the group consisting of CN, SO₂R_(f),SO₂R³, P(O)(OR³)₂,CO₂R³, P(O)R³ ₂, C(O)R_(f), C(O)R³, and cycloalkenyl groups formedtherewith wherein R_(f) is a perfluoroalkyl group of 1-10 carbonsoptionally containing one or more ether oxygens; R³ is an alkyl group of1-6 carbons optionally substituted with one or more ether oxygens, or anaryl group optionally further substituted; or, when c=0, Y may be anelectron-withdrawing group represented by the formula —SO₂R_(f)′ whereR_(f)′ is the radical represented by the formula—(R_(f)″SO₂N—(H⁺)SO₂)_(m)R_(f)′″ where m=0 or 1, and R_(f)″ is—C_(n)F_(2n)— and R_(f)″″ is —C_(n)F_(2n+1) where n=1-10.
 4. The solidpolymer electrolyte membrane of claim 3 wherein the pendant group is aradical represented by the formula: —OCF₂CF(CF₃)—OCF₂CF₂SO₃H.
 5. Thesolid polymer electrolyte membrane of claim 3 wherein the pendant groupis a radical represented by the formula: —OCF₂CF₂—SO₃H.
 6. The solidpolymer electrolyte membrane of claim 1 wherein the ionomer ispolyfluorinated.
 7. The solid polymer electrolyte membrane of claim 1wherein the non-fluorinated, non-ionomeric polymer is present in theamount of at least about 0.2% by weight, based on the weight of thesolid polymer electrolyte membrane.
 8. The solid polymer electrolytemembrane of claim 7 wherein the non-fluorinated, non-ionomeric polymeris present in the amount of at least about 1% by weight, based on theweight of the solid polymer electrolyte membrane.
 9. A catalyst coatedmembrane comprising a solid polymer electrolyte membrane having a firstsurface and a second surface, an anode present on the first surface ofthe solid polymer electrolyte membrane, and a cathode present on thesecond surface of the solid polymer electrolyte membrane, wherein thesolid polymer electrolyte membrane comprises a fluorinated ionomerhaving imbibed therein a non-fluorinated, non-ionomeric polymer, whereinthe fluorinated ionomer comprises a highly fluorinated carbon backbonehaving at least 6 mole % of monomer units having a fluorinated pendantgroup with a terminal ionic group, and wherein the non-ionomeric polymeris selected from the group consisting of a polyvinyl amine, andderivatives thereof.
 10. The catalyst coated membrane of claim 9 whereinthe polyvinylamine is polyvinylpyrrolidone.
 11. The catalyst coatedmembrane of claim 9 wherein the fluorinated pendant group is the radicalrepresented by the formula—(OCF₂CFR)_(a)OCF₂(CFR′)_(b)SO₂X⁻(H⁺)[YZ_(c)]_(d)  (I) wherein R and R′are independently selected from F, Cl or a perfluoroalkyl group having 1to 10 carbon atoms, optionally substituted by one or more ether oxygens;a=0, 1 or 2; b=0 to 6; X is O, C or N with the proviso that d=0 when Xis O and d=1 otherwise, and c=1 when X is C and c=0 when X is N; whenc=1, Y and Z are electron-withdrawing groups selected from the groupconsisting of CN, SO₂R_(f),SO₂R³, P(O)(OR³)₂, CO₂R³, P(O)R³ ₂,C(O)R_(f), C(O)R³, and cycloalkenyl groups formed therewith whereinR_(f) is a perfluoroalkyl group of 1-10 carbons optionally containingone or more ether oxygens; R³ is an alkyl group of 1-6 carbonsoptionally substituted with one or more ether oxygens, or an aryl groupoptionally further substituted; or, when c=0, Y may be anelectron-withdrawing group represented by the formula —SO₂R_(f)′ whereR_(f)′ is the radical represented by the formula—(R_(f)″SO₂N—(H⁺)SO₂)_(m)R_(f)′″ where m=0 or 1, and R_(f)″ is—C_(n)F_(2n)— and R_(f)″″ is —C_(n)F_(2n+1) where n=1-10.
 12. Thecatalyst coated membrane of claim 11 wherein the pendant group is aradical represented by the formula: —OCF₂CF(CF₃)—OCF₂CF₂SO₃H
 13. Thecatalyst coated membrane of claim 11 wherein the pendant group is aradical represented by the formula: —OCF₂CF₂—SO₃H.
 14. The catalystcoated membrane of claim 9 wherein the ionomer is polyfluorinated. 15.The catalyst coated membrane of claim 9 wherein the non-fluorinated,non-ionomeric polymer is present in the amount of at least about 0.2% byweight, based on the weight of the solid polymer electrolyte membrane.16. The catalyst coated membrane catalyst coated membrane of claim 15wherein the non-fluorinated, non-ionomeric polymer is present in theamount of at least about 1% by weight, based on the weight of the solidpolymer electrolyte membrane.
 17. The catalyst coated membrane of claim9 wherein the anode and cathode comprise a catalyst, and a binderpolymer.
 18. The catalyst coated membrane of claim 17 wherein thecatalyst is platinum.
 19. The catalyst coated membrane of claim 17wherein the catalyst is supported on carbon.
 20. The catalyst coatedmembrane of claim 17 wherein the binder polymer is an ionomer.
 21. Thecatalyst coated membrane of claim 17 wherein the ionomer comprises ahighly fluorinated carbon backbone having at least 6 mole % of monomerunits having a fluorinated pendant group with a terminal ionic group.22. The catalyst coated membrane of claim 17 wherein the anode andcathode are prepared by spreading an ink composition comprising thecatalyst and the binder polymer with a knife or blade, brushing,pouring, with metering bars, spraying, by a decal transfer process,screen printing, pad printing or by application of a printing plate. 23.The catalyst coated membrane of claim 22 wherein the printing plate is aflexographic printing plate.
 24. A fuel cell comprising a solid polymerelectrolyte membrane having a first surface and a second surface,wherein the solid polymer electrolyte membrane comprises a fluorinatedionomer having imbibed therein a non-fluorinated, non-ionomeric polymer,wherein the fluorinated ionomer comprises a highly fluorinated carbonbackbone having at least 6 mole % of monomer units having a fluorinatedpendant group with a terminal ionic group, and wherein the non-ionomericpolymer is selected from the group consisting of a polyvinyl amine, andderivatives thereof.
 25. The fuel cell of claim 24 wherein thepolyvinylamine is polyvinylpyrrolidone.
 26. The fuel cell of claim 24wherein the fluorinated pendant group is the radical represented by theformula —(OCF₂CFR)_(a)OCF₂(CFR′)_(b)SO₂X⁻(H⁺)[YZ_(c)]_(d)  (I) wherein Rand R′ are independently selected from F, Cl or a perfluoroalkyl grouphaving 1 to 10 carbon atoms, optionally substituted by one or more etheroxygens; a=0, 1 or 2; b=0 to 6; X is O, C or N with the proviso that d=0when X is O and d=1 otherwise, and c=1 when X is C and c=0 when X is N;when c=1, Y and Z are electron-withdrawing groups selected from thegroup consisting of CN, SO₂R_(f),SO₂R³, P(O)(OR³)₂, CO₂R³, P(O)R³ ₂,C(O)R_(f), C(O)R³, and cycloalkenyl groups formed therewith whereinR_(f) is a perfluoroalkyl group of 1-10 carbons optionally containingone or more ether oxygens; R³ is an alkyl group of 1-6 carbonsoptionally substituted with one or more ether oxygens, or an aryl groupoptionally further substituted; or, when c=0, Y may be anelectron-withdrawing group represented by the formula —SO₂R_(f)′ whereR_(f)′ is the radical represented by the formula—(R_(f)″SO₂N—(H⁺)SO₂)_(m)R_(f)′″ where m=0 or 1, and R_(f)″ is—C_(n)F_(2n)— and R_(f)″″ is —C_(n)F_(2n+1) where n=1-10.
 27. The fuelcell of claim 24 wherein the pendant group is a radical represented bythe formula: —OCF₂CF(CF₃)—OCF₂CF₂SO₃H
 28. The fuel cell of claim 24wherein the pendant group is a radical represented by the formula:—OCF₂CF₂—SO₃H.
 29. The fuel cell of claim 24 wherein the ionomer ispolyfluorinated.
 30. The fuel cell of claim 24 wherein thenon-fluorinated, non-ionomeric polymer is present in the amount of atleast about 0.2% by weight, based on the weight of the solid polymerelectrolyte membrane.
 31. The fuel cell of claim 30 wherein thenon-fluorinated, non-ionomeric polymer is present in the amount of atleast about 1% by weight, based on the weight of the solid polymerelectrolyte membrane.
 32. The fuel cell of claim 24 further comprisingan anode and a cathode present on the first and second surfaces of thesolid polymer electrolyte membrane to form a catalyst coated membrane.33. The fuel cell of claim 32 wherein the anode and cathode comprise acatalyst, and a binder polymer.
 34. The fuel cell of claim 33 whereinthe catalyst is platinum.
 35. The fuel cell of claim 33 wherein thecatalyst is supported on carbon.
 36. The fuel cell of claim 33 whereinthe binder polymer is an ionomer.
 37. The fuel cell of claim 36 whereinthe ionomer comprises a highly fluorinated carbon backbone having atleast 6 mole % of monomer units having a fluorinated pendant group witha terminal ionic group.
 38. The fuel cell of claim 32 further comprisinga means for delivering liquid or gaseous fuel to the anode, a means fordelivering oxygen to the cathode, a means for connecting the anode andcathode to an external electrical load, wherein the fuel in the liquidor gaseous state is in contact with the anode, and oxygen is in contactwith the cathode.
 39. The fuel cell of claim 38 wherein the fuel is analcohol.
 40. The fuel cell of claim 39 wherein the alcohol is selectedfrom the group consisting of methanol and ethanol.
 41. The fuel cell ofclaim 38 wherein the fuel is an ether.
 42. The fuel cell of claim 41wherein the ether is diethyl ether.
 43. The fuel cell of claim 38wherein the fuel is hydrogen.
 44. A process for forming a solid polymerelectrolyte membrane, the process comprising combining a fluorinatedionomer and a swelling agent to form a swollen fluorinated ionomer,forming a solution of a non-fluorinated, non-ionomeric polymer in asolvent soluble in the swelling agent, and combining thenon-fluorinated, non-ionomeric polymer solution with the swollenfluorinated ionomer, wherein the fluorinated ionomer comprises a highlyfluorinated carbon backbone having at least 6 mol % of monomer unitshaving a fluorinated pendant group with a terminal ionic group, andwherein the non-fluorinated, non-ionomeric polymer is selected from thegroup consisting of a polyvinyl amine, and derivatives thereof.
 45. Aprocess for forming a solid polymer electrolyte membrane, the processcomprising combining a fluorinated ionomer and a swelling agent to forma swollen fluorinated ionomer, forming a solution of a non-fluorinated,non-ionomeric polymer in a solvent soluble in the swelling agent, andcombining the non-fluorinated, non-ionomeric polymer solution with theswollen fluorinated ionomer, wherein the fluorinated ionomer comprises ahighly fluorinated carbon backbone having at least 6 mol % of monomerunits having a fluorinated pendant group with a terminal ionic group,wherein the non-fluorinated, non-ionomeric polymer present in the amountof about 0.2% to about 10% by weight, based on the weight of the solidpolymer electrolyte membrane, is selected from the group consisting of apolyamine, and derivatives thereof,
 46. The process of claim 44 furthercomprising the step of extracting the swelling agent and solvent afterthe non-fluorinated, non-ionomeric polymer solution is combined with theswollen fluorinated polymer.
 47. The process of claim 45 wherein thepolyvinylamine is polyvinylpyrrolidone.
 48. The process of claim 44wherein the pendant group is the radical represented by the formula—(OCF₂CFR)_(a)OCF₂(CFR′)_(b)SO₂X⁻(H⁺)[YZ_(c)]_(d)  (I) wherein R and R′are independently selected from F, Cl or a perfluoroalkyl group having 1to 10 carbon atoms, optionally substituted by one or more ether oxygens;a=0, 1 or 2; b=0 to 6; X is O, C or N with the proviso that d=0 when Xis O, and d=1 otherwise, and c=1 when X is C and c=0 when X is N; whenc=1, Y and Z are electron-withdrawing groups selected from the groupconsisting of CN, SO₂R_(f),SO₂R³, P(O)(OR³)₂, CO₂R³, P(O)R³ ₂,C(O)R_(f), C(O)R³, and cycloalkenyl groups formed therewith whereinR_(f) is a perfluoroalkyl group of 1-10 carbons optionally containingone or more ether oxygens; R³ is an alkyl group of 1-6 carbonsoptionally substituted with one or more ether oxygens, or an aryl groupoptionally further substituted; or, when c=0, Y may be anelectron-withdrawing group represented by the formula —SO₂R_(f)′ whereR_(f)′ is the radical represented by the formula—(R_(f)″SO₂N—(H⁺)SO₂)_(m)R_(f)′″ where m=0 or 1, and R_(f)″ is—C_(n)F_(2n)— and R_(f)″″ is —C_(n)F_(2n+1) where n=1-10.
 49. Theprocess of claim 48 wherein the pendant group is a radical representedby the formula: —OCF₂CF(CF₃)—OCF₂CF₂SO₃H.
 50. The process of claim 48wherein the pendant group is a radical represented by the formula:—OCF₂CF₂—SO₃H.
 51. The process of claim 48 wherein the ionomer ispolyfluorinated.
 52. The process of claim 45 wherein the conductivity ofthe membrane is at least 72 milliS/cm.
 53. A solid polymer electrolytemembrane comprising a fluorinated ionomer having imbibed therein anon-fluorinated, non-ionomeric polymer, wherein the fluorinated ionomercomprises a highly fluorinated carbon backbone having at least 6 mole %of monomer units having a fluorinated pendant group with a terminalionic group, wherein the non-ionomeric polymer is present in the amountof about 0.2% to about 10% by weight, based on the weight of the solidpolymer electrolyte membrane, and is selected from the group consistingof a polyamine, and derivatives thereof.
 54. The solid polymerelectrolyte membrane of claim 53 wherein the polyamine ispolyethyleneimine.
 55. The solid polymer electrolyte membrane of claim53 wherein the conductivity of the membrane is at least 72 milliS/cm.56. A catalyst coated membrane comprising a solid polymer electrolytemembrane having a first surface and a second surface, an anode presenton the first surface of the solid polymer electrolyte membrane, and acathode present on the second surface of the solid polymer electrolytemembrane, wherein the solid polymer electrolyte membrane comprises afluorinated ionomer having imbibed therein a non-fluorinated,non-ionomeric polymer, wherein the fluorinated ionomer comprises ahighly fluorinated carbon backbone having at least 6 mole % of monomerunits having a fluorinated pendant group with a terminal ionic group,wherein the non-ionomeric polymer is present in the amount of about 0.2%to about 10% by weight, based on the weight of the solid polymerelectrolyte membrane, and is selected from the group consisting of apolyamine, and derivatives thereof.
 57. The catalyst coated membrane ofclaim 56 wherein the conductivity of the membrane is at least 72milliS/cm.
 58. The catalyst coated membrane of claim 56 wherein thepolyamine is polyethyleneimine.
 59. A fuel cell comprising a solidpolymer electrolyte membrane having a first surface and a secondsurface, wherein the solid polymer electrolyte membrane comprises afluorinated ionomer having imbibed therein a non-fluorinated,non-ionomeric polymer, wherein the fluorinated ionomer comprises ahighly fluorinated carbon backbone having at least 6 mole % ofmonomer-units having a fluorinated pendant group with a terminal ionicgroup, and wherein the non-ionomeric polymer is present in the amount ofabout 0.2% to about 10% by weight, based on the weight of the solidpolymer electrolyte membrane, and is selected from the group consistingof a polyamine, and derivatives thereof.
 60. The fuel cell of claim 59wherein the conductivity of the membrane is at least 72 milliS/cm. 61.The fuel cell of claim 59 wherein the polyamine is polyethyleneimine.